Roll forming machine



NOV. 5, N c RUB|N ROLL FORMING MACHINE Filed April 11, 1933 4 Sheets-Sheet" INVENTOR RUBIN NORBEET c qsazwy Filed April 11, 19'35 4 Sheets-Sheet 2 [N VE 1V TOR NORBERT C. RU Bl N imQ-Qfiwflq Nov. 5, 1935. N RUB. I 2,020,042

ROLL FORMING MACHINE Filed April 11, 1933 4 Sheets-Sheet 5 INVENTOR NOEBEET c. 05m

Nov. 5, 1935. N c, RUBlN I ROLL FORMING MACHINE Filed April 11, 1933 4 Sheets-Sheet 4 INVENTOR NORBERT C. RUBIN Q a@%%% Patented Nov. 5, 1935 UNITED srATs rs'r OFFlE 2,020,042 ROLL FORMING MACHINE Application April 11, 1933, Serial No. 665,474

Claims.

' long strip of sheet metal into the first pair of rolls of the rolling machine. These rolls, being driven, grip the stock and pass it on to a second pair of driven rolls where the initial forming ta es place. As the stock is driven through the machine, each successive pair of driven rolls gradually bends the sheet metal; thus as the stock emerges from the roll forming machine, it is completely formed into the desired shape. During this forming process the sheet metal may be stretched more in one pair of rolls than in the succeeding pair so that an accumulation of stock is the result. Not only is this accumulation of the stock undesirable but usually results in the finished form being distorted to the extent that desirability of straightness and form of the finished piece is impossible.

It is obvious that if the operator of the machine were able to disengage from their drive all the pairs of rolls causing the accumulation, and allow the remaining rolls to draw the stock through the roll forming machine, such an accumulation would be impossible, thus eliminating a possibility of distortion in the finished section. Such a device wherein the operator can easily engage or disengage one or more pairs of rolls from the main driving source comprises the first object of my invention.

In a roll forming machine where all the rolls are driven it is also readily seen that as a very light gauge of stock is being formed, excessive stretch may appear between any two pairs of rolls with the result that tearing of that strip of sheet metal is inevitable. The second object of my invention also includes the provision of converting any one or more pairs of driven rolls to idler rolls by disengaging a clutch in the drive housing and thus enabling the roll forming machine to form any gauge of stock.

There are also instances during the operation of a roll forming machine when it is desirable not only to eliminate an accumulation of stock between two sets of rolls but also to stretch the sheet metal slightly between two sets of rolls. This is found desirable when the stock tends to wrinkle resulting from the irregular shape being rolled therein. It is obvious that in a roll forming machine where all the rolls are driven, the provision of slightly stretching the sheet metal can not be accomplished. In my invention I have not only provided a clutch whereby the driving source may be disengaged from one or more pairs of rolls but also a brake which is controlled by the clutch controls in such manner that, when the clutch is disengaged, the brake is applied with the desired 5 tension to the rolls. This provision forms another object of my invention.

It is possible that the operator of the roll forming machine may have one set of forming rolls which he uses almost constantly so that after arriving at a satisfactory brake adjustment for that set of rolls, it is highly undesirable to change that adjustment. Consequently, without changing the brake adjustment the operator may apply a different set of rolls to the machine. Should all the rolls be driven then all the clutches should be engaged and likewise all the brakes released, but if several pairs of rolls should be converted to idlers then the clutch and brake control should be moved to a provided neutral position wherein the clutch teeth have been disengaged but the brake not yet applied. This flexibility of roll adaptation to a roll forming machine constitutes another object of this disclosure.

Also during the life of the roll forming machine the necessity of embossing the strip of sheet metal presents itself. Invariably this operation stretches the stock to some dimension which is usually impossible to predetermine. This amount of stretch is so great that it is necessary to use special size rolls or a desirable speed for both the embossing rolls and all the preceding rolls to arrive at the proper peripheral speed and thus eliminate the large accumulation which otherwise would form. Therefore the ability to use any size of embossing rolls through the use of the clutch to disengage these and all preceding rolls from their source of power, constitutes another object of this invention. 40

i All who are familiar with this art recognize the fact that forming rolls which are used on a draw bench do not necessarily have to be of the same pitch diameter. It would therefore be impossible to use a set of draw bench rolls on a-roll forming machine because of the varying speeds resulting from the various pitch diameters of the rolls. As another object of my invention it will be seen that by disengaging all the roll spindles, except the last two or three, from their respective power source, a set of draw bench rolls can be applied to the roll forming machine and by using the last two or three rolls to draw'the stock through the rest of the rolls the variable speed element is eliminated even though the rolls are of various pitch diameters.

Another advantage gained by being able to disengage the rolls from their power source is that, when the required number of rolls to form the desired section is less than the number of roll spindles on the machine, those spindles which are unemployed may be disengaged from the main drive, resulting in a cheaper operating cost for the entire machine. This forms another object of this disclosure.

Further objects and advantages of my invention will be apparent from the following detailed description and illustrations in which:

Figure 1 is an elevational view of a cold roll forming machine illustrating only the essential features of the machine.

Figure 2 is a side elevational view of a portion of the cold roll forming machine shown in Fig. 1.

Figure 3 is a side elevational view of a portion of the cold roll forming machine as shown in Fig. l, and illustrating, in addition, an accumulation of material between the pairs of rolls.

Figure l is a view, partially in section taken along line 4-4 of Fig. 1.

Figure 5 is a view partlally in section taken along line 55 of Fig. 1.

Figure 6 is a View partially in section taken along line 66 of Fig. 1.

Figure 7 is a view partially in section taken along line 1-l' of Fig. 6.

Figure 8 is a view partially in section taken along line 8-8 of Fig. '7.

In the accompanying drawings which serve to illustrate my invention, the reference character i, represents the bed of a cold roll forming machine. (See Figs. 1, 4, and 6.) Mounted on the bed and adjacent to each other are a plurality of rear housings 2 having mounted therein for rotation a bottom spindle 3, having its opposite end carried for rotation in an outboard housing 4. Locate-d immediately above the bottom spindle 3 is a top roll spindle 5 which is also supported at one end by the rear housing 2 and at the opposite end by outboard housing 4. Supporting the bottom spindle in the rear housing is an anti-friction bearing 6 retained therein by a bearing retainer I on the outside and another retainer 8 on the inside, both being secured to the housing by screws, not shown. Adjacent to the outside of the inner race of the bearing 6 is a shoulder on the bottom spindle 3 against which the bearing 6 is retained by a spacer 9 placed against the opposite face of the bearing race.

Bearing against the opposite end of the spacer 3 and keyed to the bottom spindle 3 is a spur gear l6 having placed against its opposite face one end of another spacer H. Located on the bottom spindle 3 and between the opposite end of spacer H and one end of another spacer I2, is the inner race of a single row ball bearing I2. Serving to lock another single row ball bearing i4 against the opposite end of the spacer I2, is a standard lock nut l5 having threaded engagement with the bottom spindle 3. It is then obvious that the lock nut 15 serves to retain the bearing l4, spacer 2, bearing l3, spacer H, gear 29, spacer 9 and the bearing race 6, against the shoulder on the bottom spindle 3.

Carried on the outer races of bearing l3 and is is a worm wheel hub l6 having formed on its face, opposite from the gear, [0, a series of clutch teeth i! and supporting on its outward periphery adjacent the clutch teeth a worm gear ring i 8 (see Figures 6 and 7). Slidably keyed to the bottom spindle 3 and adjacent to the worm gear hub i6 is a sliding jaw clutch l9 having formed on one end a series of clutch teeth 20 in engaging relation with the clutch teeth H. Formed. midway the ends of the jaw clutch member I9 and 5 on its outward periphery is a flange being surrounded by a trunnion collar 2|, the trunnions thereon being engaged by the forked ends of a lever 22.

Mounted against a shoulder on the bottom 10 spindle 3 and adjacent the clutch member !9, is a brake drum 23 keyed to the spindle 3 and retained thereon by a spacer 24 mounted against its opposite face. Located between the opposite end of the spacer 24 and a standard lock nut 15 25 having threaded engagement with the bottom spindle 3, is a single row ball bearing 25. It is then obvious that the lock nut 25 serves to retain the bearing 26, the spacer 24 and the brake drum 23 against the provided shoulder on 20 the bottom spindle 3. Carrying the outer race of the ball bearing 26 is a cover plate 21 which is suitably fastened to the rear housing 2 of the roll forming machine by means of screws (not shown). 35

Mounted in the rear housing 2 for rotation on -anti-friction and in driving relation with the worm gear ring I8 is a worm 29 having mounted at its extremities two coupling halves 30, so that the worm shaft in the adjacent housing may rem ceive rotation from the worm shaft which is driven from some separate source of power. It will now be readily seen that, when the sliding clutch member I9 is in the disengaged position, being the position shown in Figure '7, and when u the worm shaft 29 is rotated, the worm gear 18 and its associated hub and bearings also rotate, but that no rotation will be imparted to the bottom spindle 3 or any of its component parts.

Opposite its bifurcated end, the lever 22 is 40 mounted with keyed relation to a shaft 3|, said shaft having its upper end carried for rocking movement in a boss 32 cast integrally with the rear housing 2. Extending beyond the opposite end of the lever 22, the shaft 3| passes through 45 another boss 33 in the rear housing and terminates in a lever 34 which is located on the under side of the roll forming machine bed I. Passing through a hole in the extremity of the lever 34, is one end of a link 35, which 'is retained therein 50 by a cotter pin 36 in the end of the link beyond the lever. The opposite end of the link 35, which is formed at right angles to its body, is contained in the upper end of a lever 37, and retained therein by means of a cotter pin 38 in 5 the end of the link passed through the lever. Extending through and with keyed relation to the hub of lever 3'! is a shaft 39 having one end mounted in the bed i of the roll forming machine having its opposite end passing through the other 60 I wall of the bed and terminating in the hub of a lever 40 to which it is keyed (see Fig. l). It is now obvious that as the lever 43 is given a rocking movement, a similar rocking movement is imparted through the link 35, the lever 34, 65 and the shaft 3! to the forked lever 22. Readily seen is the fact that as the forked lever 22 is given a rocking movement such a movement will result in a reciprocal travel of the clutch member H! on the bottom spindle 3, thus tending to engage or disengage the clutch teeth I! and 20 as the machine operator desires.

Surrounding the bottom half of the brake drum 23, (see Figs. 7 and 8) is a brake shoe 4| having contained on its inner surface a strip of 75 brake lining 42 so mounted as to have a braking engagement with the brake drum. Likewise, in a similar manner, a brake shoe 43 encases the top half of the brake drum and carries a strip of brake lining 44. Extending outwardly from the adjacent ends of the top and bottom brake shoes 4| and 43, are a pair of lugs 45 carrying a pin 46, retained therein by a cotter pin 41 passed through the end of the pin 46 beyond the face of the lug. Mounted on the pin 46 and be tween the lugs 45 on both brake shoes are two brackets 48 extending downwardly and outwardly with a parallel relation to each other. Passing through the outward extremities of both brackets 48 is a screw 49 having a right and a left hand threaded engagement with the brackets and having its unthreaded end terminating in a pilot lug 50 cast'integrally with the rear nousing 2. Above the lug 48, Figure 8, the screw 49 extends upward through the top plate 5| on the rear housing 2 and terminates in a squared end above the top plate so that a wrench can be applied to it. In evidence then is the fact that as the screw 49 is rotated, the brackets 49 are brought together or drawn apart as the operator so desires.

At the opposite end of both brake shoes, 4| and 45, (see Figures 7 and 8) there are also formed a pair of lugs 52 carrying both ends of pins 53 which are retained therein by cotter pins 54 passing through the ends of the pins beyond the lugs. Mounted on the pin 53 and outside the lugs 52 on the bottom brake shoe 4| are two links 55 extending upwardly and supporting both ends of a pin 55 which is retained by a cotter pin 51 passing through both of its ends. Mounted on pin 53 and inside the lugs 52 on the top brake shoe 43 are two links 58 extending upwardly and containing a hole through which is passed the pin 56. Also mounted on the pin 56 and between the ends of links 55 and 58 is one end of another pair of links 59 extending outwardly and having a hole therein through which is passed a trunnion 69 fixed to a block 6| located between the links 59. Also mounted on the trunnions 60 and retained thereon, together with the links 59, by a pair of cotter pins 62 are the ends of two links 53, the opposite ends of which are carried on a pin 64 supported in a lug 95 cast integrally with the rear housing 2. Carried in a semispherical hole in the top of the trunnion block 5| and retained by a cap 66 is one end of a ball end link 61 its opposite end retained in the end of a lever 58 by another cap 89 fastened to the lever by screws, not shown. The opposite end of the lever St" has a keyed relation to the shaft 3| together with the previously mentioned forked lever 22. It is now apparent that by partially rotating the shaft 32 not only is the clutch member i9 reciprocated and the jaw teeth engaged or disengaged as desired but also is the lever 68 given a rocking motion resulting in an opening or closing of the toggle arrangement comprising the links 59 and 63. Likewise in obviation is the fact that the lock formed by links 55 and 58 will be opened or closed resulting in the brake being applied or released regardless of the amount of tension previously created by the operator adjusting the screw 49. It will be noted by observance of Figures I and 8 that the levers 68 and 22 are so re-. lated that when the clutch teeth I! and 20 are engaged, the brake is released and vice versa.

Continuing with the rollspindle drive itself; immediately above the roller bearing 6 (see Figure 6) and slidably mounted, in provided ways,

lock nut 16 having threaded engagement with.

the top spindle 5, is a single row ball bearing 11. Obviously the lock nut l6 serves to definitely locate the ball bearing 11, the spacer 15, the spur gear 74, the spacer 13 and the roller bearing H on the top spindle 5 against the provided shoul-- der. Housing the ball bearing 11 is a bearing box 18 slidably mounted, in provided ways, in the rear housing 2.

Supporting these bearing boxes are an arrangement of screws, (see Figures 6 and 5).

Extending upwardly from the bearing box 10 is a central screw 19 piloted therein and having threaded engagement with the top plate 5| as it passes therethrough. Continuing upwardly the screw 19 has formed thereon a flange upon which rests a plate having therein a circular hole through which the screw extends and terminates immediately above the plate 80 with a squared end so that a wrench can be employed to rotate the screw. Against the top face of the top plate 5| and having threaded engagement with the screw 19 is a jam nut 8| provided to secure an adjustment after being made. Extending outwardly from the opposite sides of the screw I9 and coinciding with the bearing box 10, (see Figure 5) the plate 80 has formed in either terminal a hole through which are passed two screws 82 the heads of which rest on the upper surface of the plate. Extending downwardly the screws 82 pass through provided clearance holes in the top plate 5| and terminate in threaded engagement with the bearing box 10. It is now apparent that when the screw 19 is screwed downwardly the bearing box 10 and component parts are likewise forced in a downward direction and when the screw is raised the bearing box is also raised by virtue of the screws 82 and the plate 80. In a similar manner and by a similar arrangement the rear bearing box 18 is raised and lowered. Mounted with keyed relation and against a shoulder on the screw 19 between the bearing box 1|] and the top plate 5| is a sprocket 83 having a chain 84 running between it and a similar sprocket on the screw which supports the rear bearing box 18. In evidence then is the fact that as one screw is rotated, the other shall also be rotated and by virtue of both screws being similarly threaded into the top plate 5| the bearing boxes 10 and 18 move in the same direction simultaneously resulting in both top and bottom spindles maintaining a parallel relation with each other.

Mounted for rotation on a fixed center 9| in the rear housing 2 and in the proper engaging relation with the spur gear H), (see Figure 5) is another spur gear 99. Extending upwardly from the fixed center 9| is a pair of links 92 carrying in its upper end a pin 93 supporting for rotation another spur gear 94 having a proper engaging relation with the spur gear 99. Uniting the spur gear 94 in the proper relation with the spur gear 14 is a link 55 having one of its ends carried by the pin 93 and its opposite end supported by a provided hub on the gear box 10. It is now evident that when the spur gear I0 is rotated in the direction designated by the arrow 96, the spur gears 98 and 94 will receive rotation and likewise impart this rotation to spur gear 14 in the direction designated by the arrow 91. Also in evidence is the fact that as the top spindle 5 is adjusted up or down the spur gears maintain their proper engaging relation with each other by virtue of the links 92 and 95 and the floating pin 93. Obviously the sizes of the form rolls which may be applied to the roll forming machine can vary as the amount of adjustment between the top and bottom spindles.

Extending outwardly from the rear housing the bottom spindle 3 passes through a sleeve 85 which is mounted for rotation in the outboard housing 4. Immediately beyond the sleve 85 the spindle 3 terminates in a threaded portion having screwed thereon a flat sided nut 86. In a similar manner the top spindle 5 extends through another sleeve 8'! which is mounted for rotation in a bearing box 88 slidably mounted, in provided ways, in the outboard housing 4. In a like manner the top spindle 5 terminates in a threaded portion also having screwed thereon another nut 89. Contacting the top of the bearing box 88 is a screw 98 extending upwardly through the top plate 99, having threaded engagement therein and terminating in a squared end to which a wrench may be applied providing a means for locking the bearing box 88 in position after the adjustment has been made.

It is readily seen that when the spindle nuts 85 and 89 are removed from the spindles, the outboard housing 4, with its associated sleeves 85 and 81, can also be removed from the spindles to facilitate the mounting of the form rolls on the spindles. When the rolls are-in position and when the outboard housing and its component parts are replaced, the rolls are locked between the shoulder on the spindles and the, inner face of the bearing sleeves 85 and 81 by virtue of the fact that the spindle nuts 86 and 89 are tightened on the ends of the spindles. Obviously, as the pulley I90, which is mounted with keyed relation to an extension of the worm shaft 29, is rotated from any foreign source of drive, such as a motor, line shaft, etc., rotation will be imparted to the roll spindles through medium of the gear transmission in the rear housing and stock imposed between rolls on said spindles will be driven in the direction designated by arrow IOI, Figures 1, 2, 3, and 5. As the stock is progressed through the rollforming machine it gradually assumes the shape being formed in it until it emerges from the last pair of rolls being then formed into the desired shape.

As previously described, the stock I02, (see Figure 3) occasionally is excessively stretched between two pairs of rolls on the roll forming machine creating an accumulation between said rolls. I find that, by disengaging the pair of rolls causing the accumulation from their source of drive, the said accumulation disappears, by reason of the fact that the idler rolls no longer retard the passage of the accumulated material and thus cause all the succeeding rolls to draw the stock through said idler rolls.

While in this disclosure I have shown and illustrated only an ordinary jaw clutch, I wish it understood that any type of clutch capable of being engaged or disengaged as desired can be utilized and that their utilization would not involve any departure from my invention. Likewise I havedescribed and illustrated but one type of brake, although any device by which I could obtain similar results can be used without narrowing this disclosure.

Throughout this disclosure I have described the 5 clutch and brake as having such a relationship that when the clutch is disengaged the brake shall be applied and vice versa but should it be desirable to release the brake during a. disengagement of the clutch it is obvious that the screw 49 shown 10 in Figure 8, can be adjusted so that there will be no braking effect even when the links and 58 are moved to the locking position.

Also do Iwish it known that the particular mechanism and the various parts hereof illus- 15 trated and described are merely a typical embodiment of my invention and that the specific construction described herein is merely by way of illustration and not by limitation or narrowing of my claims.

Obviously, various of the features described can be omitted leaving the mechanism still operative to do certain of its work, such changes being contemplated by me and not involving any departure from my invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a roll forming machine, in combination, a plurality of lower roll spindles, a plurality of 30 upper roll spindles co-operating with the lower roll spindles, forming rolls mounted on each of said upper and lower roll spindles, the arrangement of an upper and corresponding lower roll spindle being designated as a pair of roll spindles, 35.

a housing for rotatably supporting the said pairs of roll spindles, a gear train interconnecting the upper and lower roll spindles of each pair of roll spindles, a common drive for the plurality of pairs of roll spindles, an individual positive clutch ar- 40 ranged between the common drive and the gear train of each of the pairs of roll spindles, an individual brake for retarding the rotation of the upper and lower roll spindles of each pair of roll spindles, an individual control means common to 45 each pair of roll spindles for engaging the said positive clutch when the control means is in one position, and for disengaging the said positive clutch when the control means is in a second position and for applying the said brake when the control means is in a third position.

2. In a roll forming machine wherein a sheet of metal is interposed between and passed through a plurality of pairs of uniformly driven rolls, and wherein the said sheet of metal becomes distorted and buckled between successive pairs of rolls when certain of the pairs of uniformly driven rolls cause the sheet of metal to be driven faster than other of the pairs of rolls due to the creeping or stretching of the sheet of metal caused by the shape of the form rolled therein, in combination, a plurality of pairs of roll spindles, a housing for rotatably supporting the said roll spindles, a common drive for the plurality of pairs of roll spindles, an individual positive clutch arranged between the common drive and each of the pairs of roll spindles for positively driving the said pairs of roll spindles and causing the said sheet of metal to be driven therebetween, an individual brake for retarding the rotation of each pair of roll spindles, means for disengaging the positive clutch associated with that pair of roll spindles which cause the sheet of metal to be driven faster than other of the pairs of roll spindles, thereby allowing the remaining pairs of driven roll spindles to draw the sheet of metal through and between the thus created idlerroll spindles without distortion or buckling, and means to operate the said brakes for constraining the rotation of the thus created idler roll spindles to further reduce the distortion and buckling over that eliminated by the thus created idler roll spindles.

3. In aroll forming machine wherein a sheet of metal is interposed between and passed through a plurality of pairs of uniformly driven rolls, and wherein the said sheet of metal becomes distorted and buckled between successive pairs of rolls when certain of the pairs of uniformly driven rolls cause the sheet of metal to be driven faster than other of the pairs of rolls due to the creeping or stretching of the sheet of metal caused by the shape of the form rolled therein, in combination, a plurality of lower roll spindles, a plurality of upper roll spindles co-operating with the lower roll spindles, forming rolls mounted on each of said upper and lower roll spindles, the arrangement of a lower and corresponding upper roll spindle being designated as a pair of roll spindles, a housing for rotatably supporting the said pairs of roll spindles, a gear train interconnecting the upper and lower roll spindles of each pair of roll spindles for driving the upper and lower roll spindles at substantially the same speeds, a common drive for the plurality of pairs of roll spindles, an individual positive clutch arranged between the common drive and the gear train of each of the pairs of roll spindles for positively driving the said gear train and the pair of roll spindles, and causing the said sheet of metal to be driven therebetween, an individual brake for retarding the rotation of each pair of roll spindles, means for disengaging the positive clutch associated with the gear train and that pair of roll spindles which cause the sheet of metal to be driven faster than other of the pairs of roll spindles, thereby disconnecting both the upper and lower roll spindles of the disengaged pair of roll spindles from the common drive, and thereby allowing the remaining pairs of driven roll spindles to draw the sheet of metal through and between the thus created upper and lower idler roll spindles without distortion or buckling, and means to operate the said brakes for constraining the rotation of the thus created upper and lower idler roll spindles to further reduce the distortion and buckling over that eliminated by the thus created idler rolls.

4. In a roll forming machine wherein a sheet of metal is interposed between and passed through a plurality of pairs of uniformly driven rolls, and wherein the said sheet of metal becomes distorted and buckled between successive pairs of rolls when certain of the pairs of uniformly driven rolls cause the sheet of metal to be driven faster than other of the pairs of rolls due to the creeping or stretching of the sheet of metal caused by the shape of the form rolled therein, in combination, a plurality of lower roll spindles, a plurality of upper roll spindles cooperating with the lower roll spindles, forming rolls mounted on each of said upper and lower roll spindles, the arrangement of a lower pairs of roll spindles for positively driving the said gear train and the pair of roll spindles and causing the said sheet of metal to be driven therebetween, means for disengaging the positive clutch associated with the gear train and that pair of roll spindles which cause the sheet of metal to be driven faster than other of the pairs of roll spindles, thereby disconnecting both the upper and the lower roll spindles of the disengaged pair of roll spindles from the common drive, and thereby allowing the remaining pairs of driven roll spindles to draw the sheet of metal through and between the thus created upper and lower idler roll spindles without distortion or buckling.

5. In a roll forming machine wherein a sheet of metal is interposed between and passed through a plurality of pairs of uniformly driven rolls, and wherein the said sheet of metal becomes distorted and buckled between successive pairs of rolls when certain of the pairs of uniformly driven rolls cause the sheet of metal to be driven faster than other of the pairs of rolls due to the creeping or stretching of the sheet of metal caused by the shape of the form rolled therein, in combination, a plurality of lower roll spindles, a plurality of upper roll spindles cooperating with the lower roll spindles, forming rolls mounted on each of said upper and lower roll spindles, the arrangement of a lower and corresponding upper roll spindle being designated as a pair of roll spindles, a housing for rotatably supporting the said pairs of roll spindles, driving means interconnecting the upper and lower roll spindles of each pair of roll spindles for driving the upper and lower roll spindles at substantially the same speeds, power. means for driving the plurality of pairs of roll spindles, an individual clutch arranged between the power means and the driving means of each of the pairs of roll spindles for driving the said driving means and the pair of roll spindles and causing the said sheet of metal to be driven therebetween,- means for disengaging the clutch associated with the driving means and that pair of roll spindles which cause the sheet of metal to be driven faster than other of the pairs of roll spindles, thereby disconnecting both the upper and the lower roll spindles of the disengaged pair of roll spindles from the power means, and thereby allowing the remaining pairs of driven roll spindles to draw the sheet of metal through and between the thus created upper and lower idler roll spindles Without distortion or buckling.

NORBERT C. RUBIN. 

